Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/14—Conductive material dispersed in non-conductive inorganic material
  • H01B1/16—Conductive material dispersed in non-conductive inorganic material the conductive material comprising metals or alloys
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/02—Details
  • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/12—Using specific substances
  • H05K2203/128—Molten metals, e.g. casting thereof, or melting by heating and excluding molten solder
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
  • H05K3/101—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern by casting or moulding of conductive material

Definitions

• Embodiments herein relate to liquid wire, and more specifically to liquid wire composed of a gallium indium alloy with integrated microstructures.
• PDMS polydimethylsiloxane
• FIGS. 1 A-1 E are a digital image of a scanning electron microscope (SEM) images showing various gallium containing formulations, in accordance with various embodiments.
• FIG. 3 is a digital image Initial observation of high fidelity contact transfer of metal gel patterns.
• FIGS. 4A-4D are digital images of test contact transfer patterns with particle loaded metal gel. Patterns have trace widths as fine as 0.5 mm and pitches as fine as 0.25mm, in accordance with various embodiments.
• FIG. 5 is a digital image of a patterned pressure sensor, in accordance with various embodiments.
• FIG. 6 is a graph of a strain test of an 8" trace of Metal Gel encapsulated in silicone, showing the linearity of resistance relative to degree of strain.
• FIG. 7 is an illustration of variable resistors oriented to change due to strain along either weave or weft orientations.
• FIG. 8 is a simple 1x3 grid with 10 variable resistors and a four analogue output elements, A, B, C, D. All unique pairings of output elements create a 6 element vector. By properly weighting the resistance ranges of each variable resistor we can ensure the output vector uniquely encodes every possible combination of resistances to an arbitrary fidelity.
• FIG. 9 is a digital image of a 990 MHz antenna printed from metal gel, in accordance with embodiments disclosed herein.
• FIGS. 10A-10D are several examples of trace patterns.
• 10A is a simple line which will act as a variable resistor changing with strain parallel to its path.
• 10B has a return path to allow a signal to be read with i/o ports local to each other. The vertical connecting bar will provide negligible resistance change for strain measured parallel to the main traces.
• 10C A zigzag pattern will multiply the resistance/strain feedback for strain perpendicular to the direction of the trace.
• 10D a trace with a return path and resistance/strain feedback multiplier on the horizontal portion. This trace will be sensitive to strain parallel to its orientation, but not perpendicular.
• FIG. 1 1 is a graph of a measured insertion loss to 6 GHz for of 1 .4 mil (35um) thick Cu reference trace and a 75um thick metal gel line. Insertion loss rises for both materials from skin effect.
• FIG. 13 is a block diagram of the basic strain sensor using a pair of metal gel wires of length L s .
• the Wheatstone bridge has an output V 0 , which is proportional to R s , which is fed into an ADC to create a digital strain data output.
• FIG. 14 is a block diagram showing how a diplexer allows the DC current, l s , to flow through the strain sensor loop via L d , while the RF signal is coupled by C d into the loop and removed by Ci and C2.
• the inductor L d also prevents the RF signal from being short circuited.
• FIGS. 15A-15C are three methods of creating controlled impedance transmission lines using metal gel.
• 15A A coaxial interconnect with a metal gel center (1 ) conductor (that could even be a coated nylon cord) surrounded by an insulating encapsulation layer and a metal gel outer layer (2) with a final outer encapsulation layer to stabilize the structure.
• 15B Two metal gel lines in a "twin lead” (also called “bifilar") arrangement.
• the first design (15A) has an outer conductor of metal gel (2) applied around the insulated center conductor (1 ) to create a coaxial transmission line having an impedance of the range of 30 to 100 ohms.
• the description may use perspective-based descriptions such as up/down, back/front, and top/bottom. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of disclosed embodiments.
• Coupled may mean that two or more elements are in direct physical contact. However, “coupled” may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other.
• Flexible conductors are needed for numerous applications in electronics. Wearable devices, conforming sensors, flexible displays, soft robotic actuators and stretchable interconnects all require an electrically conductive medium able to both repeatably bend and stretch. Ideally a flexible conductor should provide no material resistance to the motion of a substrate it is adhered to while maintaining conduction through many cycles of stretching and flexing. A liquid conductor is ideally suited for this task.
• liquid metal conductors use eutectic alloys of gallium, usually mixed with indium and tin, which are embedded within microfluidic channels.
• these alloys include: gallium-indium (usually 75% gallium, 25% indium) and gallium-indium-tin (most commonly 68.5% gallium, 21 .5% indium, 10% tin).
• the gallium alloy fluids have low viscosities and high surface tensions. While these alloys may be good conductors, they have significant drawbacks that have hampered their widespread adoption. For example, the alloys themselves are difficult to process. In addition, the microfluidic channels are prone to leaking or failing irreversibly if the substrate the alloy is embedded in fatigues.
• the alloys form an oxide layer on exposure to atmosphere, which is not conductive and can lead to failures at junctions between flexible wires and hard components.
• the current disclosure fulfils those needs.
• a novel composite material discovered by the inventor that is composed of a gallium alloy and gallium oxide composition that includes distributed microstructures formed from the gallium oxide within the bulk gallium alloy.
• the microstructures are formed from sheets of gallium-oxide that form on the surface of the bulk gallium to induce the distributed microstructure when mixed into the gallium alloy.
• the alloy is bound into a cross linked nanostructure of oxide ribbons, which serve a purpose similar to polymer gelling agents in common water based gels.
• the gallium oxide in conjunction with a gallium alloy fluid, form micro and nano-structures. These structures can bear a small amount of force, depending on their geometry.
• a gallium alloy fluid By distributing a very large number of irregularly shaped micro and nano-structures composed of gallium oxide through the bulk of a gallium alloy fluid a new and novel composite fluid can be created, with high viscosity and non-Newtonian rheological properties.
• the fluid behaves similarly to a Bingham Plastic, holding structure until a stress is applied.
• the creation and distribution of these micro and nano-structures can be achieved by multiple methods.
• the creation and distribution of gallium oxide micro and nano-structures is achieved by coating nano-particles and/or micro-particles in gallium-indium-tin enveloped in gallium oxide, and suspending them in a fluid of gallium-indium-tin through application of shear by means of shaking or mixing.
• an electrically conductive compositions for example with a paste like consistency, created by taking advantage of the structure provided by gallium oxide mixed into a eutectic gallium alloy in such a way as to provide micro or nano-structures capable of altering the bulk material properties of the eutectic gallium alloy.
• the an electrically conductive compositions can be characterized as a conducting shear thinning gel composition, or a material having the properties of a Bingham plastic.
• a disclosed composition has a viscosity ranging from about 10,000,000 centipoise to about
• composition has a viscosity of about
• centipoise or about 40,000,000 centipoise under conditions of low shear. Under condition of high shear the composition has a viscosity of about 150 centipoise, about 155 centipoise, about 160 centipoise, 165 centipoise, about 170 centipoise, about 175 centipoise, or about 180 centipoise.
• a disclosed composition includes a mixture of a eutectic gallium alloy and gallium oxide, wherein the mixture of eutectic gallium alloy and gallium oxide has a weight percentage (wt%) of between about 59.9% and about 99.9% eutectic gallium alloy, such as between about 67% and about 90%, and a wt% of between about 0.1 % and about 2.0% gallium oxide such as between about 0.2 and about 1 %.
• a disclosed composition can have about 60%, about
• the eutectic gallium alloy can include gallium-indium or gallium-indium-tin in any ratio of elements.
• a eutectic gallium alloy includes gallium and indium.
• a disclosed composition has percentage of gallium by weight in the gallium-indium alloy that is between about 40% and about 95%, such as about 40%, about 41 %, about 42%, about 43%, about 44%, about 45%, about 46%, about 47%, about 48%, about 49%, about 50%, about 51 %, about 52%, about 53%, about 54%, about 55%, about 56%, about 57%, about 58%, about 59%, about 60%, about 61 %, about 62%, about 63%, about 64%, about 65%, about 66%, about 67%, about 68%, about 69%, about 70%, about 71 %, about 72%, about 73%, about 74%, about 75%, about 76%, about 77%, about 78%, about
• a disclosed composition has percentage of indium by weight in the gallium-indium alloy that is between about 5% and about 60%, such as about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 1 1 %, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, about 20%, about 21 %, about 22%, about 23%, about 24%, about 25%, about 26%, about 27%, about 28%, about 29%, about 30%, about 31 %, about 32%, about 33%, about 34%, about 35%, about 36%, about 37%, about 38%, about 39%, about 40%, about 41 %, about 42%, about 43%, about 44%, about 45%, about 46%, about 47%, about 48%, about 49%, about 50%, about 51 %, about 52%, about 53%, about 54%, about 55%, about 56%, about 57%, about 58%, about
• a eutectic gallium alloy includes gallium and tin.
• a disclosed composition has percentage of tin by weight in the alloy that is between about 0.001 % and about 50%, such as about 0.001 %, about 0.005%, about 0.01 %, about 0.05%, about 0.1 %, about 0.2%, about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about 0.8%, about 0.9%, about 1 %, about 1 .5%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 1 1 %, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, about 20%, about 21 %, about 22%, about 23%, about 24%, about 25%, about 26%, about 27%, about 28%, about 29%, about 30%, about 31 %, about 32%
• one or more micro-particles or sub-micron scale particles are blended with the gallium alloy and gallium oxide.
• the particles are suspended, either coated in eutectic gallium alloy or gallium and encapsulated in gallium oxide or not coated in the previous manner, within eutectic gallium alloy fluid.
• These particles can range in size from nanometer to micrometer and can be suspended in gallium, gallium-indium alloy, or gallium-indium-tin alloy. Particle to alloy ratio can vary, in order to change fluid properties.
• the micro and nano-structures are blended within the mixture through sonication or other mechanical means.
• a disclosed composition includes a colloidal suspension of micro and nano-structures within the gallium alloy/gallium oxide mixture.
• composition further includes one or more micro-particles or sub-micron scale particles dispersed within the mixture. This can be achieved by suspending particles, either coated in eutectic gallium alloy or gallium and encapsulated in gallium oxide or not coated in the previous manner, within eutectic gallium alloy fluid. These particles can range in size from nanometer to micrometer and can be suspended in gallium, gallium-indium alloy, or gallium-indium-tin alloy. Particle to alloy ratio can vary, in order to change fluid properties. In addition, the addition of any ancillary material to colloidal suspension or gallium alloy paste in order to enhance or modify its physical, electrical or thermal properties.
• micro and nano- structures within eutectic gallium alloy can be achieved through sonication or other mechanical means without the addition of particles.
• the one or more micro-particles or sub-micron particles are blended with the mixture with wt% of between about 0.001 % and about 40.0% of micro-particles, for example about
• the particles can be soda glass, silica, borosilicate glass, quartz, oxidized copper, silver coated copper, non-oxidized copper, tungsten, super saturated tin granules, glass, graphite, silver coated copper, such as silver coated copper spheres, and silver coated copper flakes, copper flakes, or copper spheres, or a combination thereof, or any other material that can be wetted by gallium.
• the one or more micro-particles or sub-micron scale particles are in the shape of spheroids, rods, tubes, a flakes, plates, cubes, prismatic, pyramidal, cages, and dendrimers.
• the one or more micro-particles or sub-micron scale particles are in the size range of about 0.5 microns to about 60 microns, as about 0.5 microns, about 0.6 microns, about 0.7 microns, about 0.8 microns, about 0.9 microns, about 1 microns, about 1 .5 microns, about 2 microns, about 3 microns, about 4 microns, about 5 microns, about 6 microns, about 7 microns, about 8 microns, about 9 microns, about 10 microns, about 1 1 microns, about 12 microns, about 13 microns, about 14 microns, about 15 microns, about 16 microns, about 17 microns, about 18 microns, about 19 microns, about 20 microns, about 21 microns, about 22 microns, about 23 microns, about 24 microns, about 25 microns, about 26 microns, about 27 microns, about 28 microns, about
• the methods include blending surface oxides formed on a surface of a gallium alloy fluid into the bulk of the gallium alloy fluid by shear mixing of the surface oxide/alloy interface; and inducing a cross linked microstructure in the surface oxides; thereby forming a conducting shear thinning gel composition.
• a colloidal suspension of micro-structures is formed within the gallium alloy/gallium oxide mixture, for example as, gallium oxide particles and/or sheets.
• the surface oxides are blended at a ratio of between about 59.9% (by weight) and about 99.9% eutectic gallium alloy, to about 0.1 % (by weight) and about 2.0% gallium oxide.
• percentage by weight of gallium alloy blended with gallium oxide is about 60%, 61 %, about 62%, about 63%, about 64%, about 65%, about 66%, about 67%, about 68%, about 69%, about 70%, about 71 %, about 72%, about 73%, about 74%, about 75%, about 76%, about 77%, about 78%, about 79%, about 80%, about 81 %, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91 %, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or greater, such as about 99.9% eutectic gallium alloy while the weight percentage of gallium oxide is about 0.1 %, about 0.2%, about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about 0.8%, about 0.9%, about 1 .0%, about 1 .1
• one or more micro-particles or sub-micron scale particles are blended with the gallium alloy and gallium oxide.
• the one or more micro-particles or sub-micron particles are blended with the mixture with wt% of between about 0.001 % and about 40.0% of micro-particles in the composition, for example about 0.001 %, about 0.005%, about 0.01 %, about 0.05%, about 0.1 %, about 0.2%, about 0.3%, about 0.4%, about 0.5%, about 0.6%, about 0.7%, about
• the article of manufacture comprises an electronic device.
• the article of manufacture comprises a fabric, a plastic film and/or a membrane.
• the disclosed compositions are integrated in sensors, for example sensors for us in detection strain and/or shear sensing.
• deforming liquid wire composed of a disclosed composition can create measurable changes in resistance, capacitance, inductance, impedance or characteristic frequency depending on the conductor geometry.
• the compositions can be used as sensors to detect strain and/or shear on any substrate.
• a composition can be integrated into a 'geotextile' for use in reinforcing a berm or levy.
• the article of manufacture comprises an article of bodywear comprising a base fabric; and one or more elements of the disclosed composition disposed thereon.
• a base fabric for example for body gear, is disclosed that may use one or more elements of the disclosed
• a sufficient surface area of the base fabric should be exposed to provide the desired base fabric function (e.g., stretch, drape, texture, breathability, moisture vapor transfer, air permeability, and/or wicking). For example, if there is too little exposed base fabric, properties such as moisture vapor transfer and/or air permeability may suffer, and even disproportionately to the percentage of coverage.
• desired base fabric function e.g., stretch, drape, texture, breathability, moisture vapor transfer, air permeability, and/or wicking.
• the amount electrically conductive composition and/or placement is selected to contain costs and create a material that is aesthetically pleasing.
• the electrically conductive compositions has a thickness in the range from about 0.05, mm to about 5mm thick, such as about 0.05, about 0.1 , about 0.5, about 1 .0, about 1 .5, about 2.0, about 2.5, about 3.0, about 3.5, about 4.0, about 4.5, about 5.0, mm thick, or any value or range within, although lesser and greater thicknesses are also contemplated.
• the amount electrically conductive composition and/or placement may be disposed on a base fabric having one or more desired properties or characteristics.
• the base fabric may have properties such as air permeability, moisture vapor transfer, and/or wickability, which are common needs for bodywear used in both indoor and outdoor applications.
• the base fabric may have other desirable attributes, such as abrasion resistance, anti-static properties, anti-microbial activity, water repellence, flame repellence, hydrophilicity, hydrophobicity, wind resistance, solar protection, SPF protection, resiliency, stain resistance, wrinkle resistance, and the like.
• separations between the amount electrically conductive compositions may help allow the base fabric to have a desired drape, look, and/or texture.
• Suitable base fabrics may include nylon, polyester, rayon, cotton, spandex, wool, silk, or a blend thereof, or any other material having a desired look, feel, weight, thickness, weave, texture, or other desired property.
• single-layer of base fabric may be used comprising the base fabric, whereas other embodiments may use multiple layers of fabric, including a layer of the base fabric, coupled to one or more other layers.
• the placement, pattern the amount electrically conductive composition may vary.
• the pattern of the amount electrically conductive composition and/or placement may be symmetrical, ordered, random, and/or asymmetrical.
• gallium-indium and related alloys wets to any non-metallic surface is through the adhesion of its oxide layer and the resultant trapping of the fluid under that layer. It was the hypothesis that gallium-indium-tin would wet in such a manner to the beads, with a thin layer of fluid metal directly in contact with the glass, trapped in place by an oxide layer. Through mixing the glass beads would come repeatedly in contact with atmosphere, forming successive layers of oxide trapping successive layers of gallium-indium-tin. When these structures were resubmerged, shear forces from the mixing were expected to cause the oxide layers to break and form dispersed structure, allowing a colloidal suspension of the glass beads and upping the viscosity of the fluid.
• microstructures to form on the gallium-oxide surface. Successive sonication and mixing sessions blended these structures into the bulk of the fluid, eventually resulting in a gel consisting of gallium-indium-tin and approximately .84% oxide. This gel was less prone to separation than that made with glass beads and has a naturally much higher bulk conductivity. Interestingly, hydrochloric acid, often used to reduce the oxide on gallium alloys, reduces only the surface oxide on gel produced in this manner, leaving the internal structure intact. This contrast with gel made with glass beads, which is fully reduced by HCL, causing a complete separation of the beads from the gel and a lowering of viscosity.
• FIGS. 1 A-1 E show regular unprocessed gallium-indium-tin (note it is blurry because it has a very low viscosity and so is vibrating due to the electron beam impacting.
• FIG. 1 B shows a micron scale flake stabilized gel (image 500 microns across),
• FIG. 1 C shows
• FIG. 1 D shows unstabalized gel whipped into a standing shape, to show its semi-solid properties (75 microns across),
• FIG. 1 E unstabalized gel (250 microns view).
• FIG. 2A and B show unsuccessful (A, B) and successful (C compression tests side by side. Note the 'sprues' jetting off the main body of the unsuccessful compressions. These are caused by unrestrained flow of gallium metal which is moving separately from the composite system. In contrast, the particle additive loading in the successful test is such that the system must flow together and spreads evenly on compression. This is very desirable for encapsulating the conducting gel using established industrial techniques such as thermowelding plastic films around a deposited pattern. In the course of carrying out these compression tests it was observed that patterns were transferred between the substrates with very high fidelity when peeled apart (see FIG. 3)
• FIGS. 4A-4D show the initial trials with that stamp produced excellent results. Patterns with trace widths as fine as 0.5 mm and pitches as fine as 0.25mm.
• FIG. 5 shows an encapsulated stamp, with leads attached.
• the disclosed formulations enable large scale strain and deformation sensing through use of eutectic metal gel composite materials that can be printed in a manner similar to an ink or paint onto a variety of substrates in order to create conductive traces. Because the disclosed material are an amorphous room temperature fluid, they can be deformed and stretched without fatiguing. A thin trace laid down on a plastic fabric liner can flex and stretch without affecting the feel of the fabric.
• the amorphous metal structure of the disclosed materials provides that when stretched or otherwise deformed there is linear resistance change which can be used for sensing (see FIG. 6).
• resistance change can be used to measure dynamic forces and strains during parachute deployment.
• Any segment of metal gel wire will serve a variable conductor the variance of which will be a function of strain parallel to the conductor. This allows a large number of strain sensing patterns to be built, with various resolutions. In the simplest case two traces could be patterned onto each gore on a parachute, one traveling in the weft direction and one traveling in the weave direction (see FIG. 7). By measuring
• a strain profile for the individual parachute gore can be drawn. With correct patterning certain portions of traces can have a disproportionately high linear resistance change in response to strain. A zigzag pattern for example will show disproportionately high resistance change if strained in an axis perpendicular to the path of the trace. Using this feature, multiple traces could be built along a gore with appropriate patterning over an area of interest for gaining strain information. This would increase the resolution of strain sensing over the gore and allow a complete strain map to be extrapolated.
• a very high resolution could be achieved by building a mesh of
• each segment of the mesh would be a variable resistor dependent on strain in either the weft or weave direction depending on its orientation. All unique pairings of output elements create a 6 element vector. By properly weighting the resistance ranges of each variable resistor it can be ensured that the output vector uniquely encodes every possible combination of resistances to an arbitrary fidelity (see, for example FIG. 8).
• metal gel acts exactly as a metal
• electrical signals can be transmitted out either through a wired connection made of a metal gel trace running down a suspension line, or via broadcast.
• Each gore could have sewn on a small embedded system which reads out resistor values and feeds them into a standard broadcast format.
• These signals could be fed into metal gel antennas printed on the canopy surface (see FIG. 9).
• the antennas can be stretched, changing its operating frequency, however such changes are linear and can be matched for.
• a pattern of antennas broadcasting unique ID's could also provide low resolution strain maps of the canopy surface. Though possible, data transmission and strain detection through RF signals are not proposed in the Phase I proposal.
• strain would be measured directly on the canopy surface, without the need for external sources of illumination or remote detection. This would enable not only high resolution measurement of the strain field without the computational overhead of image processing, but also field deployable systems that would not be sensitive to variable light levels, adverse weather or payload/canopy misalignment.
• the objective is to adhere to the nylon material of a parachute canopy. It is not anticipated that a thin TPU trace or silicone adhesive will negatively affect the underlying material. However tensile strength and fatigue tests are done to ensure there is no negative effect. Assessment is performed for direct application of silicone based adhesives, such as Dow Corning 7091 to parachute fabric and subsequent patterning of metal gel onto the cured sealant and adhesion of TPU encapsulated metal gel traces to the canopy fabric.
• Strain testing on encapsulated metal gel traces to parachute fabric is performed to measure strain resistance feedback relationship in weft and weave directions. A variety of standard trace patterns in weave and weft orientations will be measured through the desired strain ranges of .2-25%. Characterized eutectic metal gel variable resistor values will be used.
• variable resistor mesh networks By simulating these networks with real values derived as described below will generate a mapping of the high dimensional surface network of coupled linear variable resistors to an output vector that can take on a continuous range of values. Such a mapping will be stored in a lookup table that can be used for interpreting variable resistor network outputs in larger scale experimentation.
• a small scale parachute, single gored and under 3 feet, will be patterned with two eutectic metal gel strain sensors, one for weft direction and one for weave.
• Variable resistor traces will be prepared inside TPU films. We will adhere these films to swatches of parachute canopy material measuring approximately one foot by three inches. In addition, Silicone adhesive, such as Dow Corning 7091
• canopy material swatches with integrated strain sensing traces will be mounted on an Instron 3365 testing machine outfitted with a 2 kN Load Cell and a LVDT to measure the displacement AL S .
• Quasi static strain tests will take place at strains of 0-20% in 0.25% steps.
• Dynamic strain tests will be taken over the range of 0-20% for 350 cycles on each sample. Displacement data will be collected in Labview for all tests.
• the change in resistance, AR S is measured using a Wheats!one bridge, which generates an analog output voltage, V 0 , which is a function of the change in resistance at its input.
• V 0 the input "strain" resistance
• R S V S /I S
• R s i and R S 2 resistances
• the analog output voltage, V 0 is converted to digital data by using a National Instruments ADC (Analog to Digital Converter) for analysis in Labview where it will be converted into R s data.
• the ADC has a target spatial resolution sufficient to detect a 0.25% change in voltage with a sampling rate of 1000 Hz.
• attaching this system to a microcontroller will produce a real time dynamic view of strain during parachute deployment. During this task multiple conductive patterns will be tested both in weft and weave orientations. These patterns will include trace widths of 1 -4 mm in .5mm increments in various geometries.
• a simulation model will be created in either MatLab or LabView. This model will consist of a catalogue of variable resistors with strain percentages as the input and resistance changes appropriate to the metal gel pattern as the output. This catalogue of known and characterized metal gel traces will be used below.
• variable resistor grid patterns As these are easy to build with a high density of strain sensors. However, we will not rule out other unconnected or sparsely connected variable resistor networks for high resolution sensing. The output of this task will be a set of modeled patterns which can be laid on prototype canopy systems.
• a small parachute will be purchased and two metal gel traces will be attached on one gore. One will be in the weft direction, one in the weave direction.
• eutectic metal gel to a nylon fiber parachute suspension cord can be done at room temperature with no intermediary chemical processing necessary.
• a flexible and stretchable binding agent such as 2 part polyurethane resin or silicone elastomer could be used to permanently encapsulate the gel against the nylon cord and prevent any displacement during normal handling and packing of the parachute suspension and control line systems. It is expectated that this process will leave the ultimate tensile strength and flexibility of the parachute line unchanged.
• the amorphous metal structure of disclosed compositions ensure that when stretched or otherwise deformed there is linear and repeatabie resistance change which can be used for sensing.
• a standard parachute cord such as PIA-C-5040 and integrated with a Wheatstone bridge, with an Analog to Digital Converter, these linear and repeatabie resistance changes can be used to measure dynamic forces and strains during parachute deployment.
• the resistance of Liquid Wire conductors can be engineered by adjusting thickness and width to be on the order of 1 to 100 ohms per meter, which is ideal for applications requiring resistance to be measured vs. stretch, since the resistance value is high enough to give a good signal to noise ratios in a Wheatstone bridge.
• Higher resistances, such as for CNT based conductive coatings, result in very small currents that are easily corrupted by electromagnetic interference (EMI).
• EMI electromagnetic interference
• copper has such a low resistance value that the voltage drop over a few meters of line is too small to be practical, and also suffers from EMI issues.
• Typical resistance values for a line with dimensions of a MIL-C-5040H control line measuring 6 feet in length coated with metal gel are between 2 to 20 Ohms depending on deposition thickness.
• FIG. 6 shows the strain response for a metal gel wire encapsulated in a silicone rubber.
• FIG. 1 1 shows measured insertion loss for a 50 ohm microstrip line made of copper versus metal gel.
• Other solutions using organic conductors can have several kilo-ohms of resistance, making them impractical for carrying RF signals more than a few inches.
• the Gage Factor (GF) of a 0.5 meter nylon cord with integrated metal gel trace will be characterized for axial strain sensing. This is accomplished by measuring the normalized change in resistance (AR/R) versus strain (ALA).
• the goal of this objective is to test different types of transmission lines made out of metal gel to characterize their RF signal carrying capability. This will include controlling the transmission line characteristic impedance.
• the transmission lines will be designed to be compatible with the standard parachute line cord form factor.
• Parachute lines should have their flexibility and durability substantially unaltered by the addition of a eutectic metal gel. Ultimate tensile strength of the coated lines will be measured and compared to uncoated versions. Likewise, the conductive metal gel coating should be able to stand up to the same requirements of flexibility and durability the suspension lines are held to. For this reason dynamic strain feedback will be tested by placing repeated strain on the line through 350 cycles. The objective is to see no failure on the part of the conductor or the parachute suspension line.
• strain sensing parachute lines One with an un-encapsulated coating on ail eight of the inner cords with the sheath providing encapsulation (FIG. 12B), one with two polyurethane encapsulated metal gel coated nylon inner cords providing an outgoing and return signal line (FIG. 12C), one with the same arrangement encapsulated in silicone rubber, and one with a separate TPU sensing ribbon running the length of the parachute line (FIG. 12D).
• P!A-C-5040 parachute lines with integrated strain sensing traces will be mounted on an Instron 3364 testing machine outfitted with a 5 kN Load Cell and strained until their failure point. Tests will be compared to stock parachute lines without integrated strain sensing traces. The linear range of the strain feedback from the conductive traces will be assessed over the total elongation, from 0% to failure
• R s V s /ls as shown in FIG. 13, where two metal gel wires' of length L s , have resistances Rsi and R S 2- These two wires represent the two conductors in strain sensing topologies such as shown in FIG. 12C and D.
• the analog output voltage, V 0 is converted to digital data by using a National instruments ADC (Analog to Digital Converter) for analysis in Labview where it will be converted into R s data.
• the ADC has a target spatial resolution sufficient to detect a 0.25% change in voltage with a sampling rate of 1000 Hz,
• the ratio of the change in resistance AR S to the nominal zero strain resistance R so divided by by the strain, ⁇ gives GF.
• a ttaching this system to a microcontroller will produce a real time dynamic view of strain during parachute deployment.
• the second design (B) uses a pair of close spaced conductors (3) to create a "twin lead" interconnect having an impedance on the order of 100 to 300 ohms.
• the exact impedance is a function of the metal gel dimensions, the spacing the lines, and the dielectric constant of the encapsulation material.
• the third design (C) is similar to (B), except than outer shield (4) is added to allow lower impedance values and reduce radiation and EMI. Test structures will be simulated and measured to characterize their insertion loss and characteristic impedance versus frequency. Results of the simulation and finished transmission line design will be the output of this task.
• a proof of concept transmission line, or lines will be fabricated in which a signal line will be jacketed in an envelope of conductive material impregnated rubber in order to provide EMI shielding, such as shown in FIG. 15A and C.
• the feasibility of using carbon black loaded polyurethane or silicone will be tested, as well as a shielding layer of metal gel laid over an insulating encapsulation coating an inner layer of sensing/transmission gel.
• Simulations will be performed using a 3D electromagnetic simulator such as ANSYS HFSS to model the behavior. Data from the simulations and prototype lines will be the output of this task.
• a prototype embedded system will be designed and built for reading out variable resistor values and converting them to strain percentages which can be sent out via SPI or I2C for processing elsewhere.
• a Wheatstone bridge designed to produce variable voltage ranging from 250 mV to 2500 mV will be integrated onto a board with a 12 bit ADC, a low power microcontroller and a power supply. Design and construction of a prototype board does not involve any unknown science or novel engineering and should take approximately two months, depending on turnaround with an assembly contractor. Programming of the embedded system is expected to take another month.
• Raw voltage values from the wheatstone bridge read through the ADC will need to be converted to strain percentages based on experiments run in Task 3 which will have provided the appropriate GF.
• a less certain challenge will be the packaging design for robustly interfacing metal gel conductors with contacts on the board.
• the conductive line running the length of the parachute cord will need to be contacted with a solid metal in such a way that the metal gel trace remains hermetically sealed so as to prevent displacement or contamination of the metal gel.
• We view the most likely packaging method to succeed will be splicing brass wires into the variable resistance transmission lines at their terminus, sealing the junction with a potting agent and then soldering the wires into terminals on the PCB.
• the finished system can be validated by mounting the parachute line in the Instron 3364 and imposing precise and known strains upon the line while reading data out of the embedded system.
• the outcome of this task will be a finished prototype of a parachute suspension line with metal gel enabled strain sensing attached to an embedded system which can generate data out in the form of strain percentage over either SPI or I2C data lines.
• EMI Shielding Prototyping and Testing [00138] Prototype lines consisting of a shielding layer of either metal gel or carbon black impregnated elastomer and of sensing/transmission gel so as to create a coaxial cable or shielded bifilar line, as shown in FIG. 15A and C respectively, will be physically tested. Both systems will be tested as transmission lines and their radiated emissions will be tested either by using the anechoic chamber.

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• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Conductive Materials (AREA)
• Non-Insulated Conductors (AREA)
• Manufacturing Of Electric Cables (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)
• Powder Metallurgy (AREA)
• Surgical Instruments (AREA)
• Manufacturing Of Printed Circuit Boards (AREA)
• Separation By Low-Temperature Treatments (AREA)
• Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

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• 2017
  • 2017-02-27 WO PCT/US2017/019762 patent/WO2017151523A1/en active Application Filing
  • 2017-02-27 JP JP2018545999A patent/JP7141042B2/ja active Active
  • 2017-02-27 ES ES17760557T patent/ES2900539T3/es active Active
  • 2017-02-27 EP EP21196700.5A patent/EP3975204B1/de active Active
  • 2017-02-27 EP EP17760557.3A patent/EP3424053B1/de active Active
  • 2017-02-27 HU HUE17760557A patent/HUE057538T2/hu unknown
  • 2017-02-27 PL PL17760557.3T patent/PL3424053T3/pl unknown
  • 2017-02-27 HR HRP20211886TT patent/HRP20211886T1/hr unknown
• 2022
  • 2022-08-26 JP JP2022135340A patent/JP7551050B2/ja active Active

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